A New Nonproportional Low Cycle Fatigue Life Prediction Method for Type 304 Stainless Steel

Abstract

A new method is put forward to predict fatigue life for low cycle nonproportional loading based on the Itoh criterion. The proposed method considers the multi-axiality influence on the reference maximum principal strain path and the calculation of nonproportionality factor Fnp by utilizing a multi-axial fatigue life prediction approach based on the modified Wöhler curve method. Different from the hypothesis of previous integral models for computing factor Fnp where the loading path is considered uniform, a new model using an inhomogeneous integral is presented and a path-dependent weight factor is defined to describe this inhomogeneity. The experimental tests of Itoh on 304 stainless steel with 14 different loading cases are referenced to examine the validity of the new method.